Delay line character generator

ABSTRACT

A device for generating a character upon a CRT tube consisting of a pulse generator placing a pulse upon a delay line which is capacitively coupled to three etched sense wires, the voltages induced on said wires ultimately controlling the X-deflection, the Y-deflection, and the unblanking function of the CRT tube. Before the voltages are applied to the CRT tube, the correct sense wires are selected and the voltages thereon are amplified.

United States Patent Inventor Kenneth A. Pearson Kingston, NY.

Appl. No. 713,529

Filed Mar. 15, 1968 Patented Sept. 28, 1971 Assignee International Business Machines Corporation Armonk, N.Y.

DELAY LINE CHARACTER GENERATOR 4 Claims, 4 Drawing Figs.

U.S. CI 340/324 A, 315/18, 315/30 Int. Cl H01j 29/70 Field of Search 340/324.1,

[56] References Cited UNITED STATES PATENTS 2,525,893 10/1950 Gloess 340/206 UX 3,169,240 2/1965 Macovski 340/324 3,289,195 11/1966 Townsend 340/324 3,483,547 12/1969 Henderson 340/324 Primary Examiner-John W. Caldwell Assistant Examiner-- David L. Trafton Attorney-Hanifin and Jancin ABSTRACT: A device for generating a character upon a CRT tube consisting of a pulse generator placing a pulse upon a delay line which is capacitively coupled to three etched sense wires, the voltages induced on said wires ultimately controlling the X-deflection, the Y-deflection, and the unblanking function of the CRT tube. Before the voltages are applied to the CRT tube, the correct sense wires are selected and the voltages thereon are amplified.

PATENTED same 19 1 SHEET 2 BF 3 FIG.2

PATENTE D siPzslen 3,609 .744

sum 3 0r 3 FIG.4

DEFL

LOGIC CONTROL DEFL LOGIC CONTROL DEFL LOGIC CONTROL DELAY LINE CHARACTER GENERATOR BACKGROUND OF THE INVENTION Prior attempts have been made to design a satisfactory delay line character generator. For example, one prior art device is a coil wound around a delay line, the windings of the coil having a varied pitch. A pulse is placed upon the delay line and induces in the coil a voltage of varying amplitude depending upon the pitch of the wire associated with the specific point in the delay line. This prior art device does not lend itself to mass fabrication because of the practical difficulty of producing variable pitch windings. Moreover, when more than one coil is associated with one sense wire, each coil must be wound on top of the previous coil; individual coils, other than the top coil, cannot easily be changed. Since the complete assembly of delay line and coils must then be replaced when an individual coil is changed, substitutability becomes prohibitively expensive. Moreover, these devices are not adapted for cheaply combining more than one character-generating device with each CRT tube.

Another prior art device utilizes capacitive coupling to a delay line upon which a pulse is traveling. In this device the sense wire is capacitively coupled only at discrete points and not continuously along its length. Thus, a continuous and smooth character cannot be generated upon a CRT tube. Moreover, the construction is not suitable for quick, cheap, and easy substitutability.

Therefore, an easily fabricated smooth character generator with interchangeable sense wires is not obtained by the prior art devices, Moreover, the prior art is not able to combine more than one character generator with a single CRT tube.

FIELD OF THE INVENTION The invention belongs to the field of inventions in communications, more specifically systems which provide more than two indications.

SUMMARY OF THE INVENTION The invention generates signals which when applied to the control electrodes of a cathode-ray tube, (hereinafter referred to as CRT) a character will be generated which will have smooth continuous lines, rather than sharp abrupt strokes. The invention utilizes a delay line capacitively coupled to a plurality of sense lines; each point of the sense line is associated with one point of the delay line. When a pulse is passeddown the delay line, a voltage is capacitively coupled into the sense line. By varying the distance between the sense line and the delay line the amplitude of the voltage induced in the sense line can be controlled. Thus, as the pulse travels along the delay line, a time varying voltage is produced at the output of each sense line.

More specifically, the invention utilizes a M-derived delay line see Design of Prototype Lumped-Constant Delay Lines by R. Michel, Zilberstein, Military System Design, June i963. The sense lines are mounted above the delay lines, and in the preferred embodiment consists of wires etched onto a printed circuit card. The preferred embodiment uses 64 sets of three wires each so as to be capable of generating 64 characters (the three wires represent the inputs for the x-axis, the Y-axis and the unblanking function (i.e., the electron beam control normally regulated by a grid) on the CRT).

The sense lines form the input to a selection network. The selection network consists of a separate AND circuit for each of the sense lines. The other input to each AND circuit is a selection line. By activating the specified selection line an output will appear at the desired AND circuit. The output of each AND circuit associated with an X-line forms the input to an OR circuit, the output of each AND circuit associated with the Y-line forms an input to another OR circuit, and the output of each AND circuit associated with an unblank sense line forms an input to a third OR circuit. The output of the OR circuits form the inputs to three amplifiers, respectively. The outputs of each of the amplifiers is connected to the correct control electrode on the CRT.

Therefore, it is seen that the invention consists of an easily fabricated delay line, a conventionally produced printed circuit card, and commercially available logic circuits. By utilizing the printed circuit card construction, when the characteristics of any of the generated characters is to be changed, only the cards associated with that character need by pulled and replaced.

Therefore, it is an object of this invention to produce a delay line character generator utilizing easily fabricated parts.

It is another object of this invention to produce smooth characters by continuous capacitively coupled electrical elements.

Another object is to facilitate substitutability by use of printed circuit cards for the sense lines.

It is a further object to utilize a selection and amplification system specifically adapted for a delay line character generator to couple inore than one character generator to each CRT.

DRAWINGS The foregoing and other objects, features, and advantages of the invention will be apparent from the following more particular description of the invention, as illustrated in the accompanying drawings:

FIG. 1 illustrates the preferred embodiment of the invention comprising etched printed circuit cards located over an M- derived-type delay line.

FIG. 2 is an electrical schematic of the circuit arrangement of the preferred embodiment.

FIG. 3 is a schematic of the M-derived delay line of FIG. 1.

FIG. 4 is another embodiment of the invention using more than one CRT.

DESCRIPTION OF FIG. I AND in FIG. 3

Illustrated in FIG. 1 is the preferred embodiment of the delay line character generator. As those skilled in the art will recognize an M-derived delay line, such as shown in FIG. 1, is illustrated in FIG. 3. The delay line of FIG. 3 consists of input terminals 1; inductances 3 connected in series, one end of said series of inductances connected to the first terminal of the input terminals and the other end connected to terminating resistor 7; the other end of terminating resistor 7 connected to the second terminal of input terminals I; and capacitors 5, each one emanating from a different connection between inductors 3 and terminating at the second terminal of input ter minals 1.

Referring now to FIG. 1, inductances 3 are formed by winding a continuous wire upon flat form 9. Also evidenced in FIG. 1 are terminating resistor 7, capacitors 5, and input terminals 1.

Mounted above and substantially perpendicular to form 9 are a plurality of printed circuit cards 11 (the preferred embodiment contains 64 printed circuit cards 11, but for purposes of illustration only two, printed circuit cards 13 and 15, are shown). Carried by each printed circuit card are three thin conducting lines, each electrically insulated from the others. For example, thin conducting lines l7, l9, and 21 are carried by printed circuit card 13. Although not shown in detail printed circuit card 13 is a sandwich of two cards, one card containing lines 117 and 19 on opposing sides, and the second card containing line 21 and sandwiched to the first card with line 21 facing out.

The physical dimensions of the delay line character generator shown in FIG. 1 are such that a pulse traveling through windings 3 capacitively induces a voltage in the thin conducting lines on printed circuit cards 11. The three voltages associated with the three lines on each of the printed circuit cards 11 are applied, after various processing, to the control electrodes of a CRT. As will be explained in more detail in the preferred embodiment, the three voltages are used to control the X-deflection, the Y-deflection, and the unblanked function of a CRT.

Such hardware as connectors and supports on printed circuit cards 11 have been omitted for ease of illustration and clarity.

It is recognized that the construction of the preferred embodiment can be varied within the spirit of the invention. For example, M-derived delay lines can be made entirely from printed wiring where a continuous spiral is formed by top and bottom conductors which are interconnected by plated through holes. In this type of printed circuit board, the conductors are printed over a high dielectric constant material such that the required capacity is obtained between the conductors themselves and the internal ground plane which in turn consists of a plated layer. Or again, the delay line can be comprised of cylindrical rods folded several times and isolated from each other by grounded plates. Also, rather than using sandwich construction for printed circuit card 11, other conventional multilayered printed circuit cards for three individual cards could easily be substituted.

OPERATION OF FIG. 1

When a pulse is placed upon windings 3 by a pulse generator (not shown in FIG. 1) connected to delay line 103, a voltage is induced in the thin conducting lines upon the cards associated with the delay line directly at the point where the pulse then happens to be. Depending upon the distance that the thin conducting line happens to be from the delay line at that point, the voltage will vary. For example, referring to etched thin conducting line 17 located on printed circuit card 13, a voltage of larger magnitude will be capacitively induced on thin conducting line 17 when the pulse is below point 23 then when below point 25. A direct mathematical relationship can be derived for determining the voltage induced. However, for practical situations it has been found to be less expensive to use an empirical method of determining the exact configuration of the thin conducting lines and their relationship to delay line 103 in order to obtain the desired voltage-time relationships.

As will be further explained below, each of the thin con ducting lines, after selection and amplification, are connected to the control electrodes of a CRT. Depending upon the voltage induced in the thin conducting lines as a function of time T, the display on CRT is also varied.

For example, referring to printed circuit card 13, lines 17, 19, and 21 located thereon are connected, after various processing, to the X-deflection, the Y-deflection, and the unblank function of a CRT. The voltage on line 17 would first vary from a constant high level, gradually decrease to a low level, remain at this low level for a time, increase to a level of medium magnitude, etc. Line 21 varies between two levels in a drastic fashion. Line 19 is similar to line 17 in that it varies from one level to another without necessarily drastic changes. One skilled in the art will recognize that the abrupt characteristics of line 21 are well suited to the on-off function necessary to control the unblank function of a CRT. Similarly, lines 17 and 19 are well suited for controlling the deflection patterns of a CRT in that they could either cause drastic changes, making for abrupt corners on the character trace on the face of a CRT, or for gradual changes, making a smooth rounded corner on the character pleasing to the eye.

DESCRIPTION OF FIG. 2

Referring now to FIG. 2, an electrical schematic of the preferred embodiment is diagrammed. Pulse generator 101 is electrically connected to delay line 103. Delay line 103 is a schematic representation of the delay line 103 pictured in FIG. 3. Sense lines 111, 112, 113, 1n3, are capacitively coupled to delay line 103. Each sense line is a schematic representation of the thin conducting lines pictured in FIG. 1. For example, sense lines 111, 112, and 113 could represent thin conducting lines 21, 19 and 17, respectively. Sense lines 111, 113, 1n3 form one input to logical AND circuits 211, 212, 213, 2n3, respectively. The other input to AND circuits 211,212, 213, 2n3 are selection lines 301. The output oflogical AND circuits 211, 221, 2n1 form the input to OR circuit 303; the output of logical AND circuits 212, 222, 2n2 form the input to logical OR circuit 303; and the outputs of logical AND circuits 213, 223, 2n3 form the inputs to logical OR circuit 307. The outputs of logical OR circuits 303, 305, and 307 form the input of amplifier 309, 311, and 313, respectively. The output of amplifier 309 controls the unblanked function of cathode-ray tube 315, the output of amplifier 311 controls the Y-axis deflection of cathode-ray tube 315, and the output of amplifier 313 forms the X-axis deflection of cathode-ray tube 315.

OPERATION OF FIG. 2

As noted previously in explaining the operation of FIG. 1, when a pulse is generated by pulse generator 101 and placed into delay line 103, a corresponding voltage is induced into sense lines 111 through line 3. That is, depending upon the point in the delay line at which the pulse is instantaneously located, and the distance from the point in the delay line to the sense line, the voltage is induced in the sense line inversely proportional to that distance. Depending on which character is to be generated on the face of CRT 315 one of the selection lines 301 has a voltage placed thereon. This causes the AND circuits to which that selection line forms an input to be conditioned for conduction. To produce a desired character on the CRT, a voltage is induced upon the sense lines forming an input to the AND circuits associated with that character generator so that a voltage appears at the output of those AND circuits. For example, if the selection line 301 associated with logical AND circuits 211, 212, and 213 has a voltage placed thereon, a voltage corresponding to the voltage on the sense line inputs to AND circuits 211, 212 and 213 will appear at the outputs of AND circuits 211, 212 and 213.

Similarly, since only one input to logical OR circuits 303, 305, and 307 ever has a voltage thereon (assuming only one selection line has a voltage thereon), a similar voltage will appear at the output of these logical OR circuits. The voltage output of logical OR circuits 303, 305, 307, is amplified by amplifiers 309, 311, and 313, respectively. These amplified voltages are then fed to cathode-ray tube 315 to control the respective functions.

Those skilled in the art will easily recognize that the inven tion is not limited to three sense lines or to applications concerned with cathode-ray tubes. That is, the invention broadly is the generation of a time varying voltage by the capacitive coupling of easily replaced etched printed-circuit cards to delay lines and the novel electrical selection and amplification of the signals induced upon the sense lines.

For example, another possible adaptation of the above described invention is the use of more than one CRT tube. This specific adaptation is seen in FIG. 4. Sense lines 111, 112, ln3 are connected to a plurality of selection networks 1020, 102b, 102n similar to selection network 102 in FIG. 3. The outputs of the selection networks are each connected to the control elements of difierent CRTs 3150, 315b, 315n, respectively. The output of each of the selection networks is controlled by selection lines 3010, 301b, 301n. By properly applying voltages on the selection lines 301a, 301b, 301n all the CRTs could display the same character, each CRT could display a different character, or the CRTs could display any combinations of similar or different characters simultaneously.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes including the foregoing in form and detail may be made therein without departing from the spirit and scope of the invention as claimed below.

1. A device for generating and displaying a predetermined varying voltage on a cathode-ray tube including:

a cathode-ray tube;

a delay means;

pulse-generating means connected to the input of said delay means causing a pulse to propagate through said delay means;

sense means disposed along the length of said delay means and capacitively coupled to said delay means, the magnitude of the capacitive coupling to the delay means being fixed for each point in the sense means, with the magnitude of the coupling of at least some points varying from that of some other'points, said sense means producing a varying voltage in response to a pulse traveling on said delay means in accordance with the coupling of each point in the sense means to the delay means;

conductor means. 2. A device as in claim 1 wherein there are a plurality of sense means of three conductor means each.

3. A device as in claim 2 wherein the connecting means in- 5 eludes:

an AND circuit associated with each conductor means;

a plurality of selection means, each selection means forming the second input to the three AND circuits associated with each of said sense means of three conductor means;

connecting means connecting aid sense means to said three OR circuits, the inputs of each Of 0R circuits COIl cathoderay tube f causing the cathodH-ay tube to nected to the output of said AND circuits associated with react in accordance with the capacitively induced voltage the conducm' means f the safne f y ""8 in said sense means, Said sense means comprising three ment, the outputs of said OR circuits associated with the conductor means which are capacitively associated with f y Said delay means one for the X deflecfion comm l5 4. A device as in claim 3 including an amplifier connected to the output of each of said OR circuits, the output of said amplifiers connected to the control element of the cathoderay tube corresponding to the OR circuits.

ment, one for the Y-deflection control element, and one for the grid control element of said cathode-ray tube for causing a character to be traced on the face of said 

1. A device for generating and displaying a predetermined varying voltage on a cathode-ray tube including: a cathode-ray tube; a delay means; pulse-generating means connected to the input of said delay means causing a pulse to propagate through said delay means; sense means disposed along the length of said delay means and capacitively coupled to said delay means, the magnitude of the capacitive coupling to the delay means being fixed for each point in the sense means, with the magnitude of the coupling of at least some points varying from that of some other points, said sense means producing a varying voltage in response to a pulse traveling on said delay means in accordance with the coupling of each point in the sense means to the delay means; connecting means connecting said sense means to said cathode-ray tube for causing the cathode-ray tube to react in accordance with the capacitively induced voltage in said sense means, said sense means comprising three conductor means which are capacitively associated with said delay means, one for the Xdeflection control element, one for the Y-deflection control element, and one for the grid control element of said cathoderay tube for causing a character to be traced on the face of said cathode-ray tube in accordance with the voltages on said conductor means.
 2. A device as in claim 1 wherein there are a plurality of sense means of three conductor means each.
 3. A device as in claim 2 wherein the connecting means includes: an AND circuit associated with each conductor means; a plurality of selection means, each selection means forming the second input to the three AND circuits associated with each of said sense means of three conductor means; three OR circuits, the inputs of each of said OR circuits connected to the output of said AND circuits associated with the conductor means of the same cathode-ray tube element, the outputs of said OR circuits associated with the control element of the cathode-ray tube.
 4. A device as in claim 3 including an amplifier connected to the output of each of said OR circuits, the output of said amplifiers connected to the control element of the cathode-ray tube corresponding to the OR circuits. 